The working principle of the Javamail API JAR framework in the Java class library

Javamail API is a standard API for sending and receiving emails in Java applications.It provides the function of communicating with the email server, so as to realize the operation of mail sending, receiving, viewing, and deleting.Javamail API is achieved by using the JAR framework. It is a reusable code library that can be easily used in the Java library. working principle: 1. Introduce the Javamail API JAR framework: First of all, you need to add the javamail API jar file to the class path of the Java project to use the API in the code.You can download the JAR file of the Javamail API from the official website and import it into the project, or use the construction management tool (such as Maven or Gradle) automatic management dependencies. 2. Create mail session: Using the Javamail API, you need to create an email session object, which indicates the connection with the mail server.You can create email sessions through the following code: Properties properties = new Properties(); properties.put("mail.smtp.host", "smtp.example.com"); Session session = Session.getInstance(properties); The host name of the SMTP server is set with the Properties object.Create a new email session object through the sessionstance method. 3. Create mail messages: Use the MESSAGE class to create mail messages.Email attributes such as senders, recipients, themes, and text can be set.The following is an example of creating mail messages: Message message = new MimeMessage(session); message.setFrom(new InternetAddress("sender@example.com")); message.setRecipients(Message.RecipientType.TO, InternetAddress.parse("recipient@example.com")); message.setSubject("Hello JavaMail"); message.setText("This is a test email sent using JavaMail API."); Here, the MIMEMESSAGE class is used to create a new mail message object, and the attributes such as the sender, the recipient, the theme and the text. 4. Send mail: Use the Transport class to send mail.The following is an example of sending emails: Transport.send(message); Use the Send method of the Transport class here to send mail messages.Javamail API will pass the mail message to the configuration email server, and then the server is responsible for sending the mail to the recipient. 5. Receive email (optional): If you need to receive emails, you can use the iMAP or POP3 protocol provided by the Javamail API to access the mail server and get the email in the inbox.The following is an example of receiving mail using the IMAP protocol: Store store = session.getStore("imap"); store.connect("imap.example.com", "username", "password"); Folder inbox = store.getFolder("INBOX"); inbox.open(Folder.READ_ONLY); Message[] messages = inbox.getMessages(); Here, the Store class is used to connect to the IMAP server and obtain the income box.Then, use the Folder class to open the inbox and get the mail message. The above is the working principle of the Javamail API JAR framework in the Java class library.By using the Javamail API, it can easily implement the email sending and receiving function in the Java application.